add document with external sources for .html docs (#1704)

* add document with external sources for .html docs (cf quarto-cli/pull/13026

* fix filename

Author: cscheid

docs/advanced/html/_external-sources-section.md

@@ -0,0 +1,38 @@
+---
+title: External servers used by Quarto documents
+---
+
+The HTML files produced by Quarto (`html` documents, `dashboard`s, and `revealjs` presentations) are designed to minimize external dependencies.
+
+However, on occasion, these documents might access resources hosted in external servers.
+The following is a list of such situations:
+
+- For jupyter widgets support:
+  - `cdn.jsdelivr.net`
+- If Google analytics support is enabled in websites:
+  - `www.googletagmanager.com`
+  - `www.google-analytics.com`
+- If `webtex` is chosen to be the default math rendering method:
+  - `latex.codecogs.com`
+- If multiplex mode in `revealjs` is enabled:
+  - `reveal-multiplex.glitch.me`
+- For a number of revealjs and bootswatch themes:
+  - `fonts.googleapis.com`
+- For Quarto's internal debugging tools:
+  - `esm.sh`
+  - `cdn.skypack.dev`
+- For giscus support:
+  - `giscus.app`
+- For the `placeholder` shortcode:
+  - `svg2png.deno.dev`
+- For the `video` shortcode:
+  - `www.youtube-nocookie.com`
+  - `players.brightcove.net`
+  - `www.youtube.com`
+  - `vimeo.com`
+  - `youtu.be`
+- For documents with OJS content:
+  - `static.observableusercontent.com`
+  - `cdn.observableusercontent.com`
+  - `cdn.jsdelivr.net`
+  - `unpkg.com`

docs/advanced/html/external-sources.qmd

@@ -156,3 +156,5 @@ Once you've mastered the basics, check out these additional articles to learn mo
 [Deployment](deployment.qmd) covers how to deploy both static dashboards (which require only a web host, but not a server) and Shiny dashboards (which require a Shiny Server).
 
 [Interactivity](interactivity/index.qmd) explores the various ways to create interactive dashboards that enable more flexible data exploration.
+
+{{< include /docs/advanced/html/_external-sources-section.md >}}

docs/dashboards/index.qmd

@@ -488,4 +488,6 @@ format:
 ---
 ```
 
+{{< include /docs/advanced/html/_external-sources-section.md >}}
+
 [^1]: knitr is an R package for creating dynamic documents.

docs/output-formats/html-basics.qmd

@@ -452,6 +452,8 @@ title-slide-attributes:
 ---
 ```
 
+{{< include /docs/advanced/html/_external-sources-section.md >}}
+
 ## Learning More
 
 See these articles lo learn about more advanced capabilities of Reveal: